Isolator mount for shock and vibration

ABSTRACT

An isolator mount for the active dissipation of shocks and vibrations is presented. The invention includes at least one energy dissipating element disposed between deflectable elements so as to provide soft damping for small disturbance excitations, yet remaining sufficiently stiff to mitigate large shocks. The mount transfers mechanical energy to the dissipating element via the device structure. Dissipating element mitigates the energy in shocks and vibrations as either heat or magnetic energy. A snap-together modular embodiment enables the coupling of two or more isolators for use within a wide variety of shock and vibration applications. Quasi-static tuning of one or more mounts comprising a snap-together module facilitates an active response to changing conditions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of co-pending applicationSer. No. 10/188,446, filed on Jul. 2, 2002, and claims the benefit ofU.S. Provisional Application No. 60/302,579, filed on Jul. 2, 2001. Thesubject matters of the prior applications are incorporated in theirentirety herein by reference thereto.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an isolator mount.Specifically, the invention includes an alloy or rare earth integratedwithin an active-mode isolation mechanism so as to impede both shocksand vibrations. Methods of manufacture are described facilitating theintegration of alloys and rare earths within a plastic, composite, andmetal.

2. Related Arts

Naval ships employ a wide variety of isolator mounts to impede acoustictransmissions and to protect sensitive equipment from shocks andvibrations. Presently, isolator mounts are specifically designed for alimited range of shocks and vibrations. As such, a variety of mounts arerequired to satisfy a wide range of mechanical load conditions.

Energy dissipation mechanisms employed within presently known devicesquickly degrade with use thereby requiring frequent replacement. Forexample, passive mounts comprised of rubber and metal rapidly lose theirdamping capacity. Consequently, isolator mounts are often used wellbeyond their effective lifetime thereby compromising the integrity andperformance of shipboard systems.

Active mounts with integrated electronics increase the range of shocksand vibrations effectively isolated. However, active mounts aregenerally less durable and sensitive to environmental conditions. Forexample, wires externally attached to such devices are susceptible tobreakage. Furthermore, electronics within such devices are susceptibleto the very shocks and vibrations dissipated and to damage by saltwater,ozone, and oil contaminants.

Low-frequency shocks, typically from 3 to 10 Hz, and vibrations,typically from 5 to 30 Hz, exclude many passive and active dampingdevices. For example, the effectiveness of viscoelastic dampingincreases with frequency and is therefore of limited utility at lowfrequencies. Passive damping by piezoelectric or electrostrictivedevices, also referred to as direct effect damping devices, is notparticularly useful at low bandwidths since damping is dependent uponhysteresis loops and elastic-mechanical-to-electrical energy coupling.Coupling coefficients are generally poor and total loss is insignificantat the lower dynamic range.

Piezopolymers are better direct coupling materials than piezoceramicsand electrostrictors, therefore applicable to piezo-passive dampingdevices. In a passive-mode device, a generalized matched impedancecircuit is coupled to the active ferroelectric materials so as totransfer elastic energy to heat. In a semi-active mode, the circuit isvariably tunable. However, strength and stiffness characteristicspreclude the use of ferroelectric polymers, such as PVDF and urethane,as active devices.

What is required is an isolator mount possessing both soft damping forsmall disturbance excitations and stiffness to mitigate large shocks.

What is required is an isolator mount having a high level of dampingeffective against shocks and vibrations yet which remains sufficientlystiff otherwise.

What is required is an isolator mount that functions over a wide rangeof temperature and load conditions.

What is required is an isolator mount that facilitates quasi-statictuning for adaptive passive damping.

SUMMARY OF THE INVENTION

An object of the present invention is an actively passive damping devicecapable of mitigating shocks and vibrations within a benign environment.

The present invention is a self-contained, modular shock and vibrationmount. Mounts described and claimed herein are compatible with existingnaval systems and equipment, sufficiently responsive to achievemitigation requirements, and substantially capable so as to reduceinventory needs. The invention may be configured to form variousgeometries, including cylindrical embodiments for pipes and block-likeembodiments for machinery and electronics cabinets. A snap-togethermodular embodiment with quasi-static tuning adjustment enables theinvention to address a wide variety of conditions and to facilitateresponse to changing conditions. Quasi-static tuning adjustments arecommanded automatically or remotely via a plug-in sensor ormicro-controller. The invention is both durable and resilient havingexcellent passive shock response from near dc to mid-range, typically 3Hz to 40 Hz, and vibration suppression for small excursions into thekilohertz range. The invention includes materials and damping methodsthat achieve the described mitigation while retaining design durability.

The invention is composed of one or more materials, often referred to aslossy, capable of absorbing and dissipating energy. For example, lossymaterials may passively damp shocks and vibrations when composed ofmagneto-mechanical or super-elastic alloys so as to couple mechanicalenergy to magnetism or heat. Alloys may be combined with highly durablefiber-reinforced elastomeric materials to further enhance the isolationof shocks and vibrations. Isolators may be composed of rare earthcoatings, laminated materials, and ferrous treated rare earthparticulates.

In an alternate embodiment, an electric or magnetic field is passedthrough the described materials so to actively maximize passive dampingbehavior. For example, a field may be applied to active alloys,magneto-mechanical and shape memory, embedded within a matrix. Thetuning of passive parameters is distinct from driving such mechanismsactively, since the former is essentially a quasi-static application toinduce changes in performance in response to load and/or environmentalfactors.

The present invention relies on fiber-reinforced elastomeric dampingrigidized by fiber inclusions to achieve a high stiffness yet retainviscoelastic damping properties. Fiber-reinforced elastomers includerandom or oriented short fibers integrated into a resin transfer mold orinjection manufactured matrix, one example being a thermoplastic.Fiber-reinforced elastomers may pre-stress alloy inclusions so as tofurther improve shock and vibration characteristics.

Magneto-mechanical passive damping is applicable to shocks andvibrations. For example, magnetic iron alloys are not only durable butalso transform elastic energy into magnetic energy on each cycleaccording to the ratio k²/(1−k²). If the magnetic system has a high-lossfactor, less energy is returned to the load transfer path and the shockor vibration is damped. The primary loss phenomenon is energydissipation via hysteresis, generally independent of frequency butstrongly dependent upon amplitude.

Super-elastic passive damping is applicable to shock mitigation.Super-elastic alloys function as a high-loss damping material. Thestrain required for damping is too large for some applications. However,such damping is appropriate for ship-based shock mitigation applicationswhere several inches of displacement are common. The stress cycle of asuper-elastic alloy involves a large elastic hysteresis that transformselastic mechanical energy into heat without significantly raising thetemperature of the material. Such materials damp motions from near-dc upto 80 hertz.

Alloy inclusions may include a variety of smart material alloys, whichproduce a change of dimension, shape, or stress in response to anapplied magnetic field. Materials include magnetostrictive alloys, oneexample being Fe—Tb—Dy (Terfenol-D was developed by the Naval OrdnanceLaboratory, USA), and Magnetic Shape Memory (MSM) alloys. MSM alloyscombine the large and complex shape changes of shape memory alloys andthe fast and precise response of magnetic control. Referenced materialsallow quasi-static control of isolator mounts so as to customize theirresponse to changing load conditions.

Other materials applicable to the present invention includeferromagnetic shape alloys (FMSA). The properties of FMSAs are describedby S. J. Murray, et al., in “Field-Induced Strain Under Load in Ni—Mn—GaMagnetic Shape Memory Materials,” Journal of Applied Physics, 1998.FMSAs of particular interest to the present invention are based onhigh-magnetization alloys of Fe—Ni—Co. These alloys have a largehysteresis, hence large loss and damping. Fe-based FMSAs are lessexpensive, have a broader temperature range, and are a higher authorityalternative to Ni—Mn—Ga alloys, since a larger saturation magnetizationimplies stronger response to applied magnetic fields.

The present invention also includes a thermoplastic mount incorporatingan externally constrained viscoelastic damping layer and/orferromagnetoelastic damping laminate, otherwise referred to astreatments. Treatments are individually applied or applied incombination to commercially available mounts. Described applicationsresult in a small loss in isolation (<5%) and a correspondingly largeincrease in wide band damping (>40%) to nearly dc.

The present invention is manufactured via several methods includinglamination, coating, and composite molding. Composites are constructedas pseudo-fiber composites, as described by R. E. Newnham in “MolecularMechanisms in Smart Materials,” MRS Bulletin 20–34, 1997. Composites mayincorporate structural foam to induce pressure and reduce bubbleformation.

The present invention may be fabricated via a non-conventional method ofextrusion enabling the netshape production of thermoplastic dampingelements, including formulations of Hytrel®, about an energy dissipatingmaterial. The described method not only introduces a more reliablemethod for fabricating mounts, but enables the present invention tomimic enhanced performance of a ferromagnetoelastic damping laminate ina full composite construction. Damping alloys are introduced asparticulates or fibers during the pre-mixing process. Although thepresent invention may be similarly applied to injection moldingtechniques, extrusion allows the ferromagnetoelastic materials to bealigned into virtual chains to increase damping effectiveness.

The alignment of particulates for pseudo-fiber construction is describedin “Magnetostriction, Elastic Moduli and Coupling Factors of CompositeTerfenol-D Composites,” Journal of Applied Physics, 1999. In the presentinvention, an FMSA, MSM, cobalt ferrite, or Terfenol alloy may be mixedwith a low-viscosity resin. After sieving, the mixture is degassed andprepared for particle alignment. Particles are aligned along magneticflux lines within a large magnetic field. The assembly is cured afterparticulates are aligned during thermoset and/or extrusion.

A preferred fabrication method is extrusion between two large magneticfield devices, one example being permanent magnets. The magnetic fieldand direction of extension aligns the embedded magnetic particulatesinto so-called pseudo chains oriented in a preferred direction toenhance damping. The invention maximizes passive damping characteristicsof the finished article. In some alloys, it may be desirable to addferrite so as to facilitate the alignment process. As such, it isdistinct from the related arts.

The present invention exploits the passive capability of rare earths andmetallic alloy composite materials. Terbium, Dysprosium, andferromagnetic particulates become increasingly magnetic with decreasingtemperature. At a sufficiently low temperature, pseudo-fiber alignmentof rare earth particulates within a resin is achieved in the absence ofany additional ferromagnetic particle fraction. However, this behavioreliminates many useful thermoplastics that do not set at temperaturesrequired for alignment. More exotic matrix materials may be required,adding to the cost of manufacture. Thus, another embodiment of theisolation mechanism may include randomly distributed Terfenol, FMSA, orother damping alloys.

The preferred manufacture process, either RTV or profile extrusion orinjection molding, may also include super-elastic materials, eitherribbon or short fiber inclusions, within a resin mix. Size, volumefraction, and preload of NiTi is related, just as with the rare earth orrare earth-ferromagnetic inclusions, to the pre-stress exerted by thematrix as it shrinks about the particulates. Pre-stress is furtherenhanced with structural foam. External loads transferred by the mountfurther pre-stress the particulates. Greater pre-stress will generallyimprove both passive magneto-elastic damping by Terfenol and rare earthinclusions and shock isolation by super-elastic inclusions. The relativesoftness of such materials allows for an embodiment whereby NiTi, in asuitably chosen super-elastic phase, is laminated onto the mount. Thelaminate is further coated or laminated with a durable material, oneexample being urethane.

Extrusion manufacture offers a low-cost approach to the development ofinternally damped thermoplastic products. Polymer extrusion is a viablemethod for manufacturing C-mounts. This technique utilizes an extruderto plasticate the polymeric material with correctly aligned molecularorientation as it extrudes from a shaping die. A traveling saw may beused to cut lengths of C-mount from the continuous extrusion.

Embodiments of the present invention and methods therefore facilitatedurable isolation mounts for a wide variety of shock and vibrationapplications.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of exampleonly, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of an exemplary C-mount.

FIG. 2 is a perspective view of an alternate embodiment of a C-mount.

FIG. 3 is a perspective view of a C-mount with copper wire windingsdisposed along the exterior of the mount.

FIG. 4 is a perspective view of a C-mount having magnets disposed alongthe exterior of the mount.

FIG. 5 is a perspective view with partial section view of an alternateembodiment of a C-mount with internal coatings of rare earth materials.

FIG. 6 is a perspective view with partial section view of an exemplaryD-Mount.

FIG. 7 is a graph of damping capacity versus stress amplitude comparingthe performance of several magneto-mechanical alloys.

FIG. 8 is a graph of stress versus strain showing the hysteresis for anexemplary super-elastic alloy.

FIG. 9 is a schematic diagram showing an exemplary four-pointarrangement of shock-vibration mounts between a component and mountingsurface.

FIG. 10 is a schematic diagram showing an exemplary snap-togethermulti-mount block system.

FIG. 11 is a schematic flowchart describing electronic damping viadynamic impedance.

FIG. 12 is a perspective view of an exemplary extrusion machine for theoriented manufacture of magnetostrictive composites.

FIGS. 13 a–13 d are photographs showing several mounts having dampinglayers and plates.

FIGS. 14 a–14 b are photographs of mounts comparing an unconstraineddamping mount to one embodiment of the present invention.

FIG. 15 is a schematic diagram showing an extruded C-mount withmachine-directional molecular orientation.

FIG. 16 is a schematic diagram showing an extruded C-mount withcross-directional molecular orientation.

REFERENCE NUMERALS

-   1 First layer-   2 Second layer-   3 Third layer-   4 First insert-   5 Second insert-   6 Fastener-   7 Composite shell-   8 Rigid element-   9 Damping element-   10 Top cover-   11 Bottom cover-   12 Electronics module-   13 Fill-   14 Outer damping shell-   15 Inner damping bulkhead-   16 Damping seal-   17 Flange-   18 Connector-   19 Copper winding-   20 C-mount isolator-   21 Open end-   22 Bond layer-   23 Coating-   24 Coating-   25 Magnet-   26 First half-   27 Second half-   30 D-mount isolator-   31 Multi-mount block-   32 a, 32 b Block-   35 Mount-   36 Damping layer-   37 Damping layer-   38 Microsensor patch-   39 Cap-   40 Component-   41 Cap-   42 Mount-   43 Self-tuning embedded chip-   44 Connector-   50 Mounting surface-   101 a, 101 b Alignment device-   102 Machine-   103 Composite-   104 Damping material-   105 a, 105 b Alignment device-   106 Extrusion direction-   107 Extruder die-   108 Extruded C-mount-   109 Molecular orientation

DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, a laminate embodiment of a C-mount isolator 20is shown having a first insert 4 and second insert 5 embedded within athird layer 3 and thereafter sandwiched between a first layer 1 and asecond layer 2. While c-shaped mounts are described, other shapes arepossible.

First layer 1 and second layer 2 provide structural rigidity duringnormal loading conditions. First layer 1 and second layer 2 are composedof an energy absorbing material capable of withstanding repeateddeflections and large strains. Preferred materials include spring steeland thermoplastics.

The third layer 3 is composed of a composite, polymer, or elastomer.Preferred embodiments are composed of a fiber-reinforced elastomer. Theprimary function of the third layer 3 is to provide sufficient stiffnessso as to transfer strain into the first insert 4 and second insert 5while providing a level of elastomeric damping at higher frequencies.

First insert 4 and second insert 5 are composed of various materials.For example, a magnetostrictive material may consist of either amagnetostrictive material alone or a magnetostrictive composite composedof Terfenol, cobalt ferrite, FMSA, MSM, or Metglas. In alternateembodiments, first insert 4 and second insert 5 may be composed of amagneto-memory material, preferably constrained within a third layer 3composed of a short-fiber, reinforced elastomer.

In yet other embodiments, first insert 4 and second insert 5 may becomposed of different damping alloys. For example, the first insert 4may be a magneto-mechanical alloy and the second insert 5 a shape memoryalloy both embedded within a third layer 3 composed of afiber-reinforced elastomer. First layer 1, second layer 2, and thirdlayer 3 are molded to shape and machined, via techniques understood inthe art, so as to enable attachment at either end via fasteners 6.Preferably, fasteners 6 should allow for the passage of a bolt to securethe c-mount isolator 20 between a mounting surface 50 and a shipboardcomponent 40, as shown in FIG. 9. Thickness and relative modulus of thelaminate materials are design dependent and chosen to maximize couplingof elastic energy in shocks and vibrations into heat and magneticenergies within the damping materials. The invention may employ avariety of inserts integrated with a C-mount isolator 20, eitherinternally as shown in FIG. 1 or externally as laminates as shown inFIGS. 13 c–13 d.

As is understood in the art, magneto-mechanical alloys and compositesdissipate mechanical energy as magnetic energy, whereas super-elasticalloys and elastomers dissipate energy as heat. Magnetostrictivecomposites are formed by mixing one or more powdered magnetic materials,examples including but not limited to Terfenol-D, SmPd, SmFe₂, and CbFe.Application dependent properties are tailored by elastomer type, volumefraction of ferromagnetic powder and insulated magnetic binders, andorientation of magnetostrictive particles. Preferred embodiments aresolidified having pseudo-chains therein induced via a magnetic fieldduring extrusion. The heating process may be performed in the presenceof a magnetic field with powder ground in an inert environment. Magneticand electrical properties of feedstock are chosen to optimize eddycurrent losses and maximize magnetic hysteresis attributes.

Several methods may be used to align the magnetized particulates.Referring now to FIG. 3, a copper winding 19 is shown about the exteriorof a C-mount isolator 20. The copper winding 19 aligns themagnetostrictive, rare earth or rare earth/ferromagnetic particulates ina tangential fashion when energized. Flux lines run lengthwise along theC-mount isolator 20 so that virtual chains of alloy or rare earthinclusions are aligned lengthwise along the C-mount isolator 20.Referring now to FIG. 4, an alternate method is shown wherein one ormore magnets 25 are aligned along the C-mount isolator 20 so as toinduce a radial alignment of virtual chains within the alloy.

A third method is provided whereby a C-mount isolator 20 is externallyor internally coated, using techniques known within the art, with a rareearth, examples including Terbium or Dysprosium. Referring now to FIG.5, an internal coating approach is shown whereby the C-mount isolator 20is composed of a first half 26 and a second half 27 and thereaftercoated with successive coatings 23, 24 of like or different rare earthmaterials. In some embodiments, small amounts of ferromagnetic material,such as Terfenol, FMSA, and magnetic shape memory materials may be addedto each layer. Once the coating process is completed, first half 26 andsecond half 27 are bonded together via a bond layer 22, one exampleincluding a fiber-reinforced elastomer.

Embodiments of the present invention may include an external laminateconstruction composed of magneto-mechanical alloys, Terfenol,super-elastic, and constrained layer viscoplastic laminates with a lossfactor optimized for room temperature. Referring now to FIG. 7, severalTerfenol samples are shown having a damping capacity well above unity,thereby indicating applicability to high-stress applications. Ingeneral, magneto-elastic and ferromagnetic materials are moredissipative at bias stress. A third layer 3 composed of fiber-reinforcedsilicon rubber may be used to pre-stress the alloy and to provide aprotective anti-corrosion cover. Pre-stressing is also achieved withstructural foam.

Referring now to FIG. 2, an alternate embodiment of the C-mount isolator20 is shown having a rigid element 8 onto which is attached dampingelements 9, either magneto-mechanical or super-elastic alloys,thereafter encased within a composite shell 7. The composite shell 7 iscomposed of an extruded, cast, or molded fiber-reinforced plastic. Thecomposite shell 7 may be confined between a first layer 1 and a secondlayer 2, as shown in FIG. 1. Damping elements 9 may consist of one ormore continuous layers or segmented elements along the length of theC-mount isolator 20. Damping elements 9 may be composed of a materialthat converts elastic-mechanical energy to heat energy, one examplebeing a super-elastic alloy.

Referring now to FIG. 8, the hysteresis characteristics of a typicalsuper-elastic alloy is shown in a stress-strain plane. The leftmostgraph shows a conventional shape memory alloy, whereas the rightmostshows the same material functioning in a super-elastic phase. In stillother embodiments, damping elements 9 may be composed of one or moremagneto-mechanical and super-elastic alloys.

Referring now to FIGS. 14 a and 14 b, a prior art embodiment is comparedto one embodiment of the present invention. FIG. 14 a shows anunconstrained polymer damped mount 35 wherein the laminate is neitherconstrained nor segmented. Damping is introduced by bonding aviscoelastic polymer to a series 1B or 2A C-Worthy mount manufactured bythe Northrop Grumman Corporation. FIG. 14 b shows a constrained mount 35including a damping layer 36 disposed between and attached to both mount35 and damping plate 37. The segmented PCLD treatment shown in FIG. 14 bis either single or double-sided. The constrained arrangement imposes alarge shear into the polymer during shocks and vibrations therebycausing lose via material hysteresis.

Referring now to FIGS. 13 b–13 d, various embodiments of the constrainedmount 35 are show. FIG. 13 a shows an untreated mount 35. FIG. 13 bshows a mount 35 with PLCD laminate. FIG. 13 c shows a mount 35 with asuper-elastic SMA laminate. FIG. 13 d shows a mount 35 with amagnetostrictive laminate. Preferably, damping layer 36 and/or dampingplate 37 should be positioned at locations of maximum strain.

TABLE 1 summarizes damping as a percentage increase for severaldeflections at 1 Hertz for mounts 35 shown in FIGS. 13 b–13 d and 14 b.TABLE 2 summarizes damping as a percentage increase for severalfrequencies at a 0.05-inch deflection for mounts 35 shown in FIGS. 13b–13 d and 14 b.

TABLE 1 Deflection (inches) 0.05 0.10 0.15 0.25 MagnetostrictiveTreatment 29.02% 44.87% 40.64% 47.32% Viscoelastic Treatment 38.28%47.70% 52.27% 57.17% Super-elastic Treatment 44.92% 30.37% 43.40% 46.40%

TABLE 2 Frequency (Hertz) 1 2 5 10 Magnetostrictive Treatment 29.02%26.80% 35.88% 39.86% Viscoelastic Treatment 38.28% 35.80% 38.31% 49.10%Super-elastic Treatment 44.92% 46.35% 40.64% 47.32%

Referring now to FIG. 6, an active-passive embodiment of the presentinvention is shown and referred to as a D-mount isolator 30. A typicalD-Mount isolator 30 is a fully enclosed unit with an electronics module12 secured within a fill 13 of low-density material, including but notlimited to foam. The electronics module 12 dissipates mechanicalexcitations via active electronic damping or via passive electronicdamping, as described in FIG. 11. A third damping layer 3 with one ormore first inserts 4 and second inserts 5 are enclosed between an outerdamping shell 14 and an inner damping bulkhead 15. Outer damping shell14 and inner damping bulkhead 15 are composed of an energy absorbingmaterial capable of withstanding large repeated deflections and strains,preferably spring steel. Both outer damping shell 14 and inner dampingbulkhead 15 provide structural rigidity and integrity during non-loadingconditions. Fasteners 6 secure the outer damping shell 14, third layer3, and inner damping bulkhead 15. A lightweight damping seal 16 isattached along the open end 21 of the D-mount isolator 30 and secured tothe inner damping bulkhead 15 via a flange 17 and connector 18 coupling.A top cover 10 and bottom cover 11 are attached to the outer dampingshell 14 and composed of a flexible, yet durable material capable ofwithstanding environmental conditions and contaminants present inship-based applications.

The volume of a D-mount isolator 30 is determined in part by theelectronics module 12. A small electronics module 12 is possible, sincemagneto-mechanical effects are a function of field reversal. In anactively-passive embodiment, the controller is required to switchpolarity which may be performed by a trans-impedance current sourceupstream. The switch mechanism requires a small H-bridge switcher, anelement understood in the art, integrated within the D-mount isolator30. The switcher resets the magneto-mechanical material after one ormore loads are applied to the D-mount isolator 30.

The board plane of the electronics module 12 is oriented along the shockand vibration plane and encased within a low-density fill 13 to avoidshock and vibration damage to the electronics module 12. A top cover 10and bottom cover 11 consisting of a thin sheet of polyurethane is addedto prevent exposure to and damage by oil, ozone, saltwater. A corrugatedpolyurethane is provided along the open end 21. The electronics module12 is positioned so as to avoid the introduction of shocks andvibrations.

The polyurethane provides corrosion resistance and additional electronicdamping via the direct piezoelectric effect of the urethane. Theelectrically converted elastic energy is coupled into a compactgeneralized impedance circuit mounted within the elastomeric portion ofthe C-mount isolator 20 or simply absorbed by the switcher H-bridgecircuitry of the active D-mount isolator 30.

In the D-Mount isolator 30, the third layer 3, typically afiber-reinforced silicon rubber, functions as an anti-corrosion shelland heat sink. When used adaptively in an active mode, thefiber-reinforced silicon rubber functions as a low frequency motionamplifier driven by high-power magneto-mechanical actuators.

The lightweight damping seal 16 is composed of a corrugated polyurethaneto dissipate incident wave energy through friction associated withliquid and solid phases of the foam. Polyurethane, having a simple waveshape, is embedded into the urethane foam and bonded to the surface ofD-mount isolator 30 to create a distributed vibration absorber. Theacoustic absorber integrates the distributed piezoelectric polymerbetween individual layers of absorbing foam in a thin sandwich. Thesound absorbing material is a partially reticulated polyurethane foam.

Referring again to FIG. 6, the fill 13 is composed of a highly resilientpolyurethane exhibiting higher direct coupling of elastic energy toelectrical energy. The D-mount isolator 30 exhibits direct effectdamping whereby energy is shunted as heat out of the system via a simpleresonant tank circuit. In an alternate embodiment, urethane polymerstrips are interlaced lengthwise with thicker directionalfiber-reinforced high-strength, high-stiffness elastomer strips. Theurethane extracts a small amount of energy at low frequency and a higherpercentage of energy at higher frequency harmonics. The interlacedpolymer functions as a shock mitigation cushion and the fiber-reinforcedelastomer provides large force and rigidity with actuation underaerodynamic loading.

Referring now to FIG. 9, four C-mount isolators 20 are shown disposedbetween a component 40 and a mounting surface 50 in a typicalapplication. Shock and vibration data for an exemplary applicationinclude a 12-g maximum acceleration, a 2-inch maximum deflection, a0.1-inch static deflection, a 2-inch dynamic deflection, an operatingtemperature range between −30° and +150° F., a 0.1-inch drift, a shockfrequency between 3 and 10 Hertz, and a vibration frequency between 5and 30 Hertz. The described arrangement is equally applicable to D-mountisolators 30.

The isolators described herein facilitate interlocking arrangementsthereby forming passive and active-passive implementations. Referringnow to FIG. 10, an exemplary snap-together multi-mount block 31 isshown. Each block 32 a and 32 b is representative of a C-mount isolator20 or D-mount isolator 30. Active mode devices require a micro-sensorand a self-tuning microprocessor per set. For example, apiezopolymer-based microsensor patch 38 and self-tuning embedded chip 43are attached to each actively driven isolator. Whereas, rubber orfiber-reinforced polymer caps 39, 41 and mounts 42 are attached topassively driven isolators. Connectors 44 provide communication betweenisolators.

Snap connectors between blocks 32 a and 32 b enable both x-axis andy-axis signal and power conductivity. Jumper options select signal andpower conductivity paths enabling individual blocks 32 a, 32 b to beconfigured in a variety of arrangements. The terminal unit is the onlyunit that has a rubber-shielded microprocessor insert. The remainingunits have resilient rubber caps 39, 41. Systems utilize either a singlesensor, preferred embodiments employ a silicon MEMS device, or sensorsin several units within a distributed controller design. The remainingunits have flexible inserts. The described systems are self-encapsulatedand require a single upstream trans-impedance current source.

A multi-mount block 31 may be attached to a spring-loaded canister andthereafter clamped to a pipe. Temperature compensation may be in-builtby adjusting a reset magnetic circuit in the magneto-mechanical portionof the system.

Referring now to FIG. 12, one possible orientation of the preferredmanufacture process is shown whereby solidification of a ferromagneticpowder into pseudo-chains is enabled by a pair of alignment devices 101a and 101 b. The alignment devices 101 a, 101 b are aligned and flushmounted at the extrusion exit so as to induce magnetic flux lines in adesired orientation within the first insert 4 and second insert 5 ordampening element 9 during cool down. As the material travels in theextrusion direction 106, the alignment devices 101 a, 101 b induce thedesired solidification alignment. A second set of alignment devices 105a and 105 b may reside within the machine 102 so as to induce additionalpre-alignment during the heating process. Example machines 102 includeinjection molding and extrusion equipment understood within the art.

The emergent composite 103 may also include one or more pre-aligneddamping materials 104. Damping materials 104 are integrated into thecomposite 103, for example a short fiber-reinforced elastomer, duringactual extrusion. The composite 103 is cleaved after exiting the machine102 to the desired length. The alignment devices 101 a, 101 b mayinclude permanent magnets, magnetic field effect devices, EMP(electromagnetic pulse) devices, and cool magnets.

Referring again to FIG. 12, the fabrication process uses a stationaryhigh magnetic flux density arrangement that causes alignment as thematerial extrudes and before cooling is initiated. Damping alloyparticulates are aligned at high temperature, since they become lessferromagnetic at lower temperatures. This behavior is advantageous tosemi-passive mount isolator designs. The disappearance of magneticresponse by the magnetostrictive particulates may allow the introductionof a second set of magnetic particles, such as AlNiCa, which may be usedto “internally” tune the mounts damping parameters. A static magnet orcoil may be used to induce the necessary magnetic bias across the mount.The system becomes an RL equivalent circuit as the static value ischanged or an external resistance is modified through the simple dial-uprotation of NdCo bias magnets.

As the polymer emerges from the die with some exit velocity, it ispulled by take-up equipment through a cooling medium, such as a waterbath. A key process variable is the take-up ratio (TUR) of line velocityto exit velocity. The line velocity established by the take-up equipmentis generally higher than the die exit velocity.

The main challenge to using extrusion manufacture lies in the nature ofmolecular alignment during extrusion. Due to the parabolic nature of thevelocity profile, there is a high tendency for alignment in the machinedirection. That is for a typical L/D of 10, the alignment of moleculesor fiber whiskers is in the direction of the flow field at the outlet.

Molecular orientation of the polymer is an important characteristic thatdetermines the final mechanical properties of the mount. Referring nowto FIG. 15, an exemplary extruder die 107 and extruded c-mount 108 areshown. In conventional extrusion processes, the predominant molecularorientation 109 is in the direction at which the polymer emerges fromthe extruder die 107, also called the machine direction (MD). As such,the extruded c-mount 108 is stronger along its MD axis.

Two mechanisms contribute to MD orientation. Shear stresses cause thechain-like molecules to orient along the flow direction, as the polymerflows through the die. A TUR greater than one stretches the extrudedc-mount 108 to further favor MD orientation that is frozen as thepolymer solidifies.

When a product has a predominant direction of orientation, it is said tohave anisotropic properties. In terms of tensile strength, anisotropyresults when a product is stronger along a first axis and weaker along asecond axis perpendicular to the first axis. In the present invention,it is advantageous to extrude mount material in a manner that favors CDorientation and tensile strength.

Referring now to FIG. 16, an extruded C-mount 108 is shown withmolecular orientation 109 along its CD axis. CD orientation may beachieved by a shear flow that aligns molecules in the CD and a TUR thatminimizes MD orientation.

Magnetic particulates, one example being commercial grade AlNiCo, areintroduced directly into the composite 103 at a Curie temperature belowthe magnetization temperature of the ferromagnetic particulates tocreate an internal, and moreover tunable, RL equivalent impedance.

Preferred embodiments are composed of MSM alloys wherein the magneticfield moves microscopic parts of the material, referred to twins,thereby creating a netshape change of the material. This mechanismenables more complicated shape changes than conventional linear strain,such as bending and shear. FMSA powder/polymer micro-composites are madewith a layer of soft magnetic material, for example Fe—Co, to enhanceresponse to magnetic fields by exchanging coupling for reduced dchysteresis, lower eddy-current loss, and lower actuation field. A lowactuation field is particularly advantageous to enable quasi-statictuning of mounts for variable load applications.

Short fibers are added to the composite 103 during the manufacturingprocess to form a polymeric treatment so as to become an integral partof the exterior lamination. Adjusting the spacing between and/or lengthof the fibers optimizes the damping characteristics of the treatmenteither during or after manufacturing. The resulting treatment providesincreased vibration damping without a constraining layer. Fiberorientation is critical to the effective attenuation of vibration.

The description above indicates that a great degree of flexibility isoffered in terms of the invention. Although the present invention hasbeen described in considerable detail with reference to certainpreferred versions thereof, other versions are possible. Therefore, thespirit and scope of the appended claims should not be limited to thedescription of the preferred versions contained herein.

1. An actively passive isolator mount for shock and vibration isolationcomprising: (a) a C-shaped damping element comprising a resilient matrixand a plurality of magneto-mechanical inclusions enclosed within saidresilient matrix; (b) a rigid C-shaped outer damping shell capable ofwithstanding repeated deflections and strains; (c) a rigid C-shapedinner damping bulkhead capable of withstanding repeated deflections andstrains, said C-shaped damping element disposed between and fastened tosaid C-shaped outer damping shell and said C-shaped inner dampingbulkhead so that said actively passive isolator mount has an open endand an interior cavity, said open end having a first side attachable toa rigid structure and a second side attachable to a component residingwithin said rigid structure; (d) a damping seal flexibly disposed andattached to said actively passive isolator mount at said open end; (e) apair of covers flexibly disposed and attached about said outer dampingshell, said damping seal and said covers being non-load bearing andsealing said interior cavity from environmental conditions andcontaminants; (f) an electronics module which resets saidmagneto-mechanical inclusions non-mechanically after one or more loadsare applied to said actively passive isolator mount thereby dissipatingshock and vibrations, said electronics module oriented within saidcavity parallel to shock and vibration; and (g) a low-density fillfilling said cavity and isolating said electronics module from shock andvibration.
 2. The actively passive isolator mount of claim 1, whereinsaid C-shaped damping element dissipates mechanical energy as heatenergy.
 3. The actively passive isolator mount of claim 1, wherein saidC-shaped damping element dissipates mechanical energy as magneticenergy.
 4. The actively passive isolator mount of claim 1, wherein saidC-shaped damping element has a plurality of randomly oriented shortlength fiber inclusions.
 5. The actively passive isolator mount of claim1, wherein said C-shaped damping element has a plurality of short lengthchaff inclusions.
 6. A multi-mount block for shock and vibrationisolation comprising at least two actively passive isolator mounts ofclaim 1 communicatively attached so as to individually respond to loadconditions.
 7. A multi-mount block for shock and vibration isolationcomprising at least two actively passive isolator mounts of claim 1communicatively attached so as to mutually respond to load conditions.